| Image Processing Toolbox | |
Perform two-dimensional convolution
Syntax
C = conv2(A,B)
C = conv2(hcol,hrow,A)
C = conv2(...,shape)
Description
C = conv2(A,B) performs the two-dimensional convolution of matrices A and B, returning the result in the output matrix C. The size in each dimension of C is equal to the sum of the corresponding dimensions of the input matrices minus one. That is, if the size of A is [ma,mb] and the size of B is [mb,nb], then the size of C is [ma+mb-1,na+nb-1].
C = conv2(hcol,hrow,A) convolves A separably with hcol in the column
direction and hrow in the row direction. hcol and hrow are both vectors.
C = conv2(...,shape) returns a subsection of the two-dimensional convolution, as specified by the shape parameter. shape is a string with one of these values:
'full' (the default) returns the full two-dimensional convolution.'same' returns the central part of the convolution of the same size as A. 'valid' returns only those parts of the convolution that are computed without the zero-padded edges. Using this option, size(C) = [ma-mb+1,
na-nb+1] when size(A) > size(B).For image filtering, A should be the image matrix and B should be the filter (convolution kernel) if the shape parameter is 'same' or 'valid'. If the shape parameter is 'full', the order does not matter, because full convolution is commutative.
Class Support
All vector and matrix inputs to conv2 can be of class double or of any integer class. The output matrix C is of class double.
Remarks
conv2 is a function in MATLAB.
Example
A = magic(5)
A =
17 24 1 8 15
23 5 7 14 16
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
B = [1 2 1;0 2 0;3 1 3]
B =
1 2 1
0 2 0
3 1 3
C = conv2(A,B)
C =
17 58 66 34 32 38 15
23 85 88 35 67 76 16
55 149 117 163 159 135 67
79 78 160 161 187 129 51
23 82 153 199 205 108 75
30 68 135 168 91 84 9
33 65 126 85 104 15 27
See Also
xcorr, xcorr2 in the Signal Processing Toolbox User's Guide
conv, deconv in the MATLAB Function Reference
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